Definitions for **"Alternate interior angles"**

When two parallel lines are cut by a transversal, the two pairs of angles on opposite sides of the transversal and inside the parallel lines, and the angles in each pair are congruent

Two nonadjacent interior angles on opposite sides of a transversal.

A transversal cutting across two or more parallel lines forms equal angles on opposite sides of the transversal and between the parallel lines.